Theory and Practice
by Alexandra Spar
Summary: HGSS. After Voldemort's final defeat, one of Snape's old students finds herself faced with a new and seemingly insurmountable challenge. Although the Dark Lord has lost, the effects of his presence have left a painful legacy with those once close to him.


Disclaimer: Harry Potter, all characters thereof, and all related indicia are the property of JK Rowling. No copyright infringement is intended and no money is being made.

A/N: This was originally written a while back, when I first got my current job, and it shows. It's been edited to remove some of the more egregious errors.

"You can tell it's almost Christmas," said Hartley Grey sourly, "because instead of wanting us to make gallons of antihistamines, they want gallons of synthetic eggnog, and they want it yesterday." He was standing at the black-topped lab bench, stirring something over a Garfein burner with the tip of his wand, and didn't look as if he was enjoying it.

"Come, come," I said. "Surely the spirit of the holidays is filling you to the brim with delight and anticipation." Grey was too damn easy to bait; we'd all fallen into the habit of it. He looked over, favouring me with an expressive sort of glare, and stuck out his tongue. I laughed. "Only two more weeks, and we'll be off for Christmas, eggnog or no eggnog. Stop looking like a Lethifold's laundry and help me aliquot this potion."

Grumbling, Grey came around the bench and picked up a pipetter, muttering the activating spell under his breath. Together we transferred the contents of my beaker into twenty glass vials and sealed each one with wax and a murmured incantation. I noticed that his hands were shaking a very little, and his pronunciation of the Latin was a bit off. Maybe there really was something bothering him besides his innate sourness. I wondered if there was a way to find out.

As it turned out, I needn't have wondered. The lab meeting we usually had at noon had been pushed back a few hours, and by the time we all got in, our white lab robes not looking their best under the harsh lamps, Grey was fairly vibrating with anxiety and looking for someone to tell. He couldn't even wait until the clinical roster was read out before blurting "Severus Snape is coming here."

Silence fell. Murgatroyd, the chief mediwizard of the division and head of our lab, closed his eyes and sighed. "Hartley," he said. "Haven't I told you that we've got such a thing as need-to-know around here? Who else have you told?"

Grey didn't even have the grace to look embarrassed. "The reception area was buzzing with it," he said. "Everyone knows."

"I didn't," I said. "You mean Severus Snape who used to teach at Hogwarts? The one with the Merlin's Cross _with_ the Oak Leaves and Wands? The one who got the Ministry grant to study long-term effects of exposure to Dark artifacts?"

"Yes," said Murgatroyd thinly, "that one." He shook his sleeves back and folded his hands neatly. "Now that everyone is aware of this, shall we move on?"

I listened with half an ear to the droning voices talking about increased incidence of influenza type A and respiratory syncytial virus and the work Brenner's lab was doing on epitope mapping and Chandra's work on the use of certain potions to affect expression of viral genetic material, but mostly I was thinking about Severus Antonius Snape and the last time I'd seen him.

It had been a cool, brisk afternoon in spring, just after graduation. We'd had the grace of two days to get all our stuff together and have it shipped off home, and most of us had, understandably, spent it getting hammered at the Three Broomsticks. I'd just about sobered up by then and was taking a walk—not thinking of it as my last walk, with an effort—around the lake. It wasn't warm outside yet, but things were beginning to be green, and there was that faint wonderful scent in the air that means you've made it through another nasty winter and there will be long hot nights to come.

The giant squid was lazily waving its tentacles in the air. I watched it for a while, idly tossing pebbles into the water, and jumped quite high when I heard someone behind me say "He likes acorns, you know. Old brown ones."

Snape was standing there with his collar turned up and his hands jammed into his pockets, looking inscrutable. It was something he did well.

I couldn't think of anything at all to say, so I bought some time by sifting through the drifts of last year's leaves for an acorn or two. I could feel him watching me. It hadn't been the easiest of years for anyone, what with the ending of the Second Voldemort War and the dismantling of the Order of the Silver Serpent. Lives had been lost; lives had been changed. I couldn't ever forget the day Dumbledore's voice rang magically out in every classroom with the simple and wonderful words: the war is over.

Snape didn't come back for almost a month after the armistice was declared, and when he did return he was a shadow of his former Snapeness. Harry and Ron and I hardly recognized him. And the worst, and strangest, part was how I suddenly seemed to lose the ability to speak when I was around him, as if something inside me was closing like a fist. I'd avoided him. Avoided meeting his eyes, as I was doing now. I couldn't help thinking of another time he and I had met by this lake. In the snow.

My fingers closed around a soggy black-brown acorn buried under the leaves. I brought it out and offered it to him, like a glass of wine or a wedding ring. He inspected it gravely, and nodded. I tossed the acorn into the water, and was unsurprised to see the squid scoop it up delicately with the tip of one tentacle and hoover it up.

"Well," I said, since he wasn't saying anything.

He continued to say nothing, staring out into the steel-coloured water. "What will you do after graduation?" he asked, eventually. I was glad to be back on familiar ground.

"I've got an internship at the Oxford Medicothaumic Institute," I said. "Potions."

Snape's face changed briefly, flickered into an expression that could almost have been a smile. "I thought you might try that," he said mildly. "You've always been one of the better Potions students in your year."

"Thank you, Professor," I said. Where was he going with this? He hadn't ever, to my memory, asked me a question that wasn't school-related and didn't have the sting of possible points off my House. Of course, that was rather moot now, since I had already passed the final exams, but I had a feeling that kind of question was what he was used to. And, because I wasn't thinking very hard, I asked him a question back. "What will you do?"

He blinked. I have only seen Snape surprised once or twice in my life, and I'll lay money on it that he wasn't expecting anyone to ask him that. "Keep teaching, of course. It's what I do."

"Of course," I murmured, and threw the squid another acorn. Silence fell.

"I'll be interested to watch your progress, Miss Granger," he said at last. "Very interested."

When I turned around to stare at him, he was gone. I've never met a non-Animagus who is so astonishingly good at vanishing without even a minor thunderclap.

I shook myself. Murgatroyd was talking to me.

"What? Sorry, I was miles away."

"I was saying," said Murgatroyd, fiddling with his pocket thaumic field indicator, "that I had thought you would already be aware of Snape's visit. Surely you Hogwarts alumni keep in touch with one another?"

I didn't feel like telling him that I'd not spoken one word to anyone from Hogwarts since I left the place more than a year before. I'd waved absently to Colin Creevey as I happened to pass him in the quadrangle or line up behind him at the market, but I hadn't even sent an owl to Harry or Ron or Ginny or any of the other Hogwarts crew. It...I don't know how to explain this...it was a totally different world back there. Talking to them would have been like talking to a stranger. I had been one person at Hogwarts: I was another at Oxford. "Well, you know how it is," I told Murgatroyd lamely. "It's so hard to keep up with where people are."

He frowned at me, but turned back to the blackboard and snapped his fingers at a piece of chalk, which jerked up into the air and began writing in his energetic and illegible hand. Classic doctors' handwriting, we called it. The agenda for the meeting and the schedule for the next month's worth of lectures appeared line by line, and we all dutifully copied it down. The meeting went on, as meetings did.

When Murgatroyd, Brenner and Chandra had all spoken, and their respective students and technicians had finished taking notes, we drifted out of the room again with the brownian motion of those not really looking forward to their destinations. I lingered.

"Professor," I said. Murgatroyd looked up from his notes.

"Yes, Granger?"

"Professor...why is Snape coming here?"

He squinted at me. "You don't know?"

I stifled a desire to snap _If I knew, why would I ask_, and merely shook my head. Murgatroyd sighed.

"He's on sabbatical. The WWN's been very close-mouthed about the whole thing, but the general idea is that it's for health reasons."

"Which is why he's coming here?"

"So I gather," said Murgatroyd. "St. Mungo's is apparently not good enough for the great war hero; he's got to come to a bloody teaching hospital and disrupt everyone's research."

I was surprised at the crossness in his tone. The OMI was indeed both a clinical facility and a research organization, but the arrival of one patient—no matter how famous—was unlikely to disrupt the laboratory of a minor researcher in antiviral potions.

_War hero?_

I gathered up my notes and went back to the bench. There was a particularly knotty bit of mixing and diluting to be done on the current batch of analgesic potions, and I couldn't afford to be wondering about Snape while I was supposed to be pipetting and measuring.

Later, much later, I sat on the steps of the Camera and had a cigarette, thinking about the day. It was Hartley Grey who'd said it was winter, and something had clicked in my mind, even before he'd told me Snape was shortly to re-enter my life. Another winter, perhaps. A winter some years back, and something surprising and unexpected happening to a young and stupid girl in the snowy groves by the lake. Funny how that damn lake kept showing up in my memories. Funny.

I had been, oh, must be sixteen, very much the bluestocking, and Harry and I had been carrying on a sort-of-relationship for a couple of months. I'd arranged to meet him by the lake at lunchtime, after my advanced Potions and before his Transfiguration, and like every man since the dawn of time, he was late. I was pacing around impatiently, my nose getting redder by the minute, and I wasn't looking where I was going or listening to the sounds of the snow around me, and I happened to walk straight into the little grove into which Severus Snape had just collapsed.

One minute there was just drifting snow, the next there was a heap of black robes and black hair lying crumpled under the boughs of the fir trees, and the sharp tin flavour of magic in the air. There was an old pocketknife lying beside him, which must have been a Portkey, but at the time I wasn't thinking about how he'd got there. I didn't realize it was him, not at first; I had a confused impression of a gigantic fluttering bat, or a misdirected vampire, but after a moment he groaned and rolled over, and there was my hated Potions master lying full-length in the snow.

I can't even put into words what went through my head; there was an almost intolerable urge to laugh—his hair was soaking wet and plastered to his face, and with the wet snow sticking to his cheeks he looked less like Snape and more like a bedraggled Goth—and a kind of horrified pity. Then he got himself propped up on one elbow, leaned over, and was extremely sick.

I quit thinking at that point and went over and held his head for him. He was ice-cold and shuddering, his face greyish with what I now know must've been shock. He went on throwing up for quite a long time. When he was done I put my cloak around him and promptly ran out of ideas—I didn't want to know what he'd do when he recognized me, and I had no idea what was wrong with him, or what to do about it. He solved the problem for me.

"Granger," he croaked. "Your wand."

I fumbled in my sleeve and handed it to him; his hands were shaking so badly that the tip of the wand described little oscillating curves in the air. He closed his eyes and leaned against me for a moment—I don't know if he was aware of it—and muttered something under his breath; the wand flickered brightly and dimmed again, and he sat up with a deep breath. When he handed the wand back to me I could _feel_ the energy missing from it.

Snape struggled to his feet and stared at me. "What are you doing out here, Granger?"he demanded, as if I had given the wrong answer in class rather than holding his hair out of the way while he was sick. The tone of voice worked, though; I stood up straight and assumed the soldier's parade rest posture we all used when he yelled at us.

"I was just going for a walk, sir," I said. _Please don't let Harry get here just now. He's already late; please let him be later._

"Hm," said Snape, and swallowed painfully. "Well. You shouldn't be out here alone, there are dangerous creatures about."

_Transparent way of saying "help me back to the castle," _I thought. _Oh well, my date with Harry wasn't really that important, and you look like you'd make it about halfway there on your own before collapsing. _"Yes, sir. Would you accompany me back?"

"I suppose I must," said Snape. He pulled my cloak tighter around his shoulders and set off unsteadily toward Hogwarts. I followed close enough for him to lean on my shoulder, and by the time we made it to the lower entrance I was taking quite a lot of his weight. _What the hell happened to him? _I wondered. _Where had he been?_

I walked with him to the Headmaster's office, and he gave me back my cloak with a stern injunction not to go walking around by the lake alone. With that, it was over—the strangest little episode in my acquaintance with Snape—and I was lucky I had exams to worry about, so that I could forget about it as quickly as possible.

Now, two and a bit years later, I pitched the cigarette end away and got up, wandering back toward my rooms at All Souls. It would not do to think about Snape now, not when we were so close to finding a potion that would cure influenza. I needed my mind on the job. All of it.

I was woken up at six the next morning by Grey hammering on my door with a sheaf of paper from the research cohort in Africa, and by the time we'd got the security guards to let us into the building, set up the registers, and recorded all the data, it was lunchtime. I cornered Grey with a pair of forceps and required him to take me out for something to eat, and preferably drink.

The OMI's cafeteria isn't that bad, actually. It's hospital food for the patients, but for people like Grey and me, who are only there for research and our clinical rotations, there are relatively edible things like deep-fried chicken fragments and boxed Caesar salads. Grey had forgotten his OMI ID, so he had to pay full price for our food, and I pleasantly selected the most expensive fare on offer. I don't think he even noticed. He was too excited about the African data and, of course, Snape. I opened a bottle of mineral water and proceeded to pump him on the subject of my old professor, and with a little coercion he began to tell me what he knew.

"Well," he said. "You know how I'm dating Heather in Pulmonology? She's doing her clinical rotation under Haversham this year and she's really getting into it, she thinks she might want to do that for her degree, you know—" He waved a chicken leg expansively. "I don't think clinical medicine is where _I_ want to go, but she seems to like it, and so I guess I can only be supportive, you know? She's willing to be flexible, of course, and maybe we can do our postdocs at the same institution or something..."

"Grey," I said. "Snape."

"Oh, right. So anyway she told me the other night that her department suddenly got all this extra Ministry funding that they hadn't applied for, and you know how bizarre that is." I did. Funding was like, well, gold, and just about as hard to get; every single possible expenditure for a grant had to be documented in triplicate and reconciled with the final business proposal, and generally such things needed to be applied for about a year and a half before the money was actually going to be needed. "She asked Haversham about it, of course, and he told her that it's because the Institute is going to be accepting a patient with peculiar needs and they have to have the money to back up research on his afflictions."

"That's more than bizarre," I said. "That's not how the Institute works."

"Hell, I know that," said Grey. "But that's what Haversham said. And a couple days after that she heard through the grapevine that Snape was this patient they were expecting, and she had to go talk to him again, you know, to verify. Turns out he's really coming here for medical help."

"And of course all our projects have to be put on hold for him, yes?" I asked, thinking about Murgatroyd's bitterness the day before. He nodded.

"Which is why I wanna get this antiviral stuff done now. Have you got any results yet?"

"No," I told him. "Flu's a bitchy virus. Murgatroyd wants to isolate one coherent and continuous characteristic for all the known strains, you know, to try and get something that recognizes the basic form of influenza without being confused by the multiple strains, but we're not getting much by way of results. I honestly think it's not worth it—we should keep doing vaccine work on flu but move on to something else that doesn't bloody mutate every year each time a new avian or porcine strain comes into being."

"Yeah, well," said Grey. "At least now we have more data to play with and a much larger bank of epitopes with the African cohort. Finish your lunch and let's go do some work."

_Damn,_ I thought. _I wanted to know more about Snape. What's wrong with him? Why is he coming here? We're by no means the forefront of clinical care in __Britain_

Nevertheless I got up and followed him out of the cafe, back across the quad to the Crowley Research Building.

That afternoon I had ward rounds with the rest of the first-year students. The OMI demanded that all the applicants to its medicothaumic degree program experience both lab science and clinical patient care, and I was one of the lucky ones who enjoyed both. Grey hated clinic sessions; he'd keep his hands tucked firmly into the pockets of his white robe, teeth clenched, as the attending mediwizard showed us a particularly nice intussusception or a fruitful case of osteomyelitis. I have to give him credit for remaining on the ward for every clinic session; several of the more romantic and willowy students had had to bolt from the room when the attending demonstrated the clinical manifestations of gas gangrene or peritonitis. He never looked interested, but he never fainted or had to excuse himself from the room. I couldn't quite figure him out.

It was Pulmonology today, surprisingly enough; my personal favourite subject, both because I was intellectually interested in the workings of the lungs and because the attending we had for that particular section was a very attractive young doctor with jet-black hair and piercing green eyes, who reminded me of someone who, I am sure, will be immediately obvious. He was Armenian, or something, and his accent was delightful. We had already visited cases of aspiration pneumonia, chronic obstructive pulmonary disorder, and one particularly interesting aspergilloma case currently recovering from surgical resection, and now he ushered us into a private room with the curtains mostly drawn and the head of the bed raised all the way up. As our eyes adjusted to the gloom, we could tell that the woman who lay there was in very serious condition.

"You will not have seen this before," said the doctor, whose name was Artanian. "It is a syndrome we have tentatively entitled 'postumbraic multisystem degeneration.'"

Someone who hadn't been doing their lessons raised a hand. "Postumbraic?"

"'After the shadow,'" said Grey annoyedly. "More or less."

There was a murmured chorus of astonishment. I don't think any of the other students there felt exactly what I felt at that moment; none of them had been to Hogwarts, and none of them had seen firsthand what a Death Eater looked like in the flesh, nor what its victims went through. Dr. Artanian waved a hand for silence; we could all hear the woman's labored respiration. "PMD seems to be rising in incidence among all those who were exposed to high levels of Dark magic during the war," he said. "It is characterized by a progressive and so far irreversible degeneration in the body's vital functions, beginning with the failure of the bone marrow to produce white blood cells, then a decline in the red blood cell count and development of pernicious anemia. The respiratory system is the next to be attacked, beginning with the failure of the cilia to remove irritants and consequent buildup of secretions and infectious foci. The immune system becomes compromised; the gastrointestinal tract loses tone and motility. We have found ways of slowing the progression of the disease, but no cure exists as yet."

I felt myself go cold all over. How many people had been in the play of Voldemort's power during the last days of the war? How many of us would be here, like this woman, struggling for breath as our bodies slowly fell apart under a curse no one had any idea how to break?

The other students, who hadn't had the benefit of being there to see Voldemort in action, were clustering around Artanian with questions. I was the only one who went over to the bed and met the eyes of the woman who lay there on display.

"Where were you?" I asked quietly.

"I worked at the Ministry," she gasped. "I was only there by accident the day he destroyed the west wing and part of the courtyard. It was so _bright_...there was this green flash, and then I don't remember anything until the Aurors were dragging us out..." She broke off in a fit of painful coughing. I waited, with the comforting patience I was being taught. "What's going to happen to me?" she managed, after a while.

"We'll take care of you," I promised, and shot a glance at Artanian. "We're working on it." _Aren't we? Why the hell are we all playing silly buggers with influenza type A when this is killing people here and now?_

Dr. Artanian came over. "Indeed we are," he said smoothly. "Don't worry, Mrs. Clearwater. Everything will be all right. You're at the forefront of scientific magic here at the OMI."

_Clearwater_

"Did you have a daughter at Hogwarts?" I blurted out, unable to stop myself.

"Yes," she murmured, surprised. "Penny. She's got a bloke in the Ministry—Percy something...red hair..."

"I...went to school with her," I said. The change in Mrs. Clearwater was remarkable: she sat up, her breathing urgent and uneasy, her face aware and alive rather than slack and accepting of her doom. The doctor looked at me with a mixture of surprise and apprehension; he was worrying, I suppose, about what I would do next to upset the patient. I merely shrugged. "I didn't know her well. She was friends with my friends." _More or less, that is._

"Is she...?" Mrs. Clearwater trailed off and I knew she was wondering if her daughter was suffering from the same thing she was.

"I don't know," I told her gently. "She graduated before I did. I'm sure she's fine."

"We've got to move on," said Dr. Artanian. He put a slender steel grip on my shoulder and walked me out of the room, looking every inch the concerned clinician.

Later they turned me loose again, and I found myself climbing blindly to the top of St. Mary's tower, feeling my way in the dark up the spiral staircase, up the ladder and finally out onto the blustery walkway that circled the tower itself at the base of its spire. The church lay beneath me; on one side I could see the Radcliffe Camera and the cobbled streets separating it from Brasenose and All Souls, on the other the high street and the watermeadows stretching away to the skyline. I was crying, of course. It didn't matter there; no one could see me, and I knew no one would say anything when I returned to the lab with puffy eyes and red lines on my face. Partly that made me cry harder and partly it helped; I felt safe there, as I hadn't felt safe to really cry anywhere since the sanctity of the girls' bathroom was invaded by the mountain troll my first year at Hogwarts. I suppose it was a neurosis of mine.

I was crying for all of us, I guess. All of us who'd been there in the shadow and who were cursed by it, and I was crying because I hadn't been told about it, and crying for Harry, whom I still loved with a bit of myself I'd forgotten about, and who was certain to get this PMD thing with all the times he'd been near Voldemort, and I was mostly crying because Artanian had taken me into his office and calmly and firmly told me the fuck off for speaking to the patient about personal matters without his leave. I curled up in the shelter of one of the corner doorways and cried and cried and cried until I felt sick and I was about as attractive as the gargoyles spitting cold drizzle from all four corners of the tower. I wanted to go home and crawl into bed and forget the whole day had ever happened.

And yes. I was crying for Snape, at least a little; it would not be easy to see that particular icon of taciturnity brought low, not easy to reconcile the Snape I had known to the one I would no doubt see on the wards one day with the same rapid painful respiration as Penny Clearwater's mum. Of course I was crying for Snape.

I'd said nothing about the episode by the lake to him, of course, nor had I mentioned it to anyone else. I went on being Granger the Brain in his class, waving my hand hopelessly when it was clear he wanted to taunt someone else for not knowing the answer, getting everything so near perfect that he accused me of cheating. That didn't bother me as much as it might have, since part of me knew it was high praise; he couldn't believe it was true that anyone could be that good. However, I couldn't help listening with a different ear when they talked about him, how he was evil and dangerous and out for his own gains. Maybe he was, but I'd never seen him look as sick as he did that day in the snow by the lake, and I couldn't honestly believe Snape was out for his own gains if it did _that_ to him. Snape never struck me as a masochist, although, looking back on it, he must have been a bit of one. Living down there in the Slytherin dungeons where the walls wept every time it rained and you could hear the creaking of the living rock as the castle shifted on its foundations...

No, I never said anything about it to Snape, but I found myself looking on him a little more kindly, adding a little less to the general current of Snape-bashing I heard every day in the Gryffindor common room. He didn't change towards me at all that I noticed, which was probably all for the best—I don't know what I would have done if he suddenly singled me out from the crowd of reluctant Potions students and, I don't know, thanked me or something. Luckily no such thing ever happened, since it would have made my life awfully difficult.

I remember sitting there in the middle of a two hour stretch of Potions, looking through the lens of an Enlargement Charm at a slide I was supposed to be analyzing, and while my self-propelling quill wrote its neat notes on width of capillaries, free lumen space, interstitial membranes and cell structure, I contemplated Snape.

He was tall and thin and walked like he was in a hurry to get somewhere, unless he was monitoring the rows of students under his care, in which case he walked with agonizing slowness, hands clasped behind his back, posture perfect and rigid. The only human thing about him was his hair, which generally fell in lank elflocks around his thin face and swayed as he moved. The rest of him could have been an automaton. He always wore unrelieved black, without even the Hogwarts crest pin that a lot of the teachers wore, or the Slytherin badge; just high-collared, close-buttoned black. His eyes were black, his hair was black, his clothes were black. If he'd been a bit better at it, he could have fooled us all into thinking his own personal world had no colour in it, that he was a picture snapped in black and white rather than a living person. I found myself drawing him occasionally, that hawk profile found its way into my absent lecture-doodles more than once, but I never spoke to him about anything that wasn't work related, nor did I make an effort to get to know him better. I was terrified of him, of course, all of us were, but in a way the incident by the lake made me less scared of him and more scared _about_ him, if that makes any kind of sense. It wasn't until much later that I became scared _for_ him.

As I was scared now. Partly because he was such a forceful person that I couldn't imagine him being reduced to the invalid state Mrs. Clearwater was in; partly because I had no real idea what exactly he'd been doing with Voldemort, and partly because, hell, he was my old teacher, and if you hate someone for seven years you find yourself really rather liking them in a backwards kind of way.

I got to my feet and made my way down the tower steps again, and home. I couldn't do anything about it today, but tomorrow I'd do my damnedest to find out what the etiology, incidence and mortality of PMD was; then I'd...

I didn't know. But I'd do something, that was certain. Before he got here, I'd do...something.


End file.
